The present invention relates to a transit seat which is particularly suited for use in a mass transportation vehicle, such as a bus or a rapid transit train.
Plastic shells have been used in transit seats, the principal advantages being in lower costs of maintenance and manufacturing. Also, inserts for plastic shells are known. Examples of such inserts are described in U.S. Pat. Nos. 3,737,198 and 3,797,887. The inserts may be padded for additional comfort so as to provide a somewhat more luxurious seat than a conventional plastic shell while maintaining the basic qualities of durability, economy, and ease of maintenance inherent in the plastic seats. The inserts further provide the ability to design a desired color scheme into the seat. In the event of vandalism to the inserts, which cover the largest exposed portion of the seat, an individual insert which is damaged can be removed and replaced.
The prior art teaches using several screws to secure the inserts to the plastic shell. Accordingly, to replace an insert the screws must be removed and replaced. Furthermore, a longitudinal seat is mounted with the seat back facing either the side walls or the back wall of a transit vehicle thereby requiring removal of the transit seat for access to the inserts securing screws. This may require removal of screws structurally mounting the transit seat to transit vehicle and the removal of adjoining trash shields and similar fittings surrounding the transit seat. Analogously, a transverse seat typically has a back cover secured by a plurality of screws which must be removed to obtain access to the screws holding in the insert. After the insert is replaced the back cover must again be secured by screws. A typical back cover for a two passenger seat has a number of screws exceeding ten. Thus, to remove one insert, a plurality of screws must be unscrewed and rescrewed. Further, the screws holding the back cover are typically self-threading and hold less tightly with successive rescrewings into the same hole. As a result, removal of an insert from either a transverse or longitudinal transit seat presents the possibility of loss of screws and replacement of the insert, the back cover and the seat frame with less than a full complement of screws. Replacement time is obviously related to labor costs and time out-of-service for the bus.
The prior art also includes U.S. Pat. No. 3,948,557 which teaches an elongated insert restraining bar, rotationally secured to the plastic shell, with notches rotated into position to engage studs protruding from the back of the insert. One end of the rectangular bar is engaged with a portion of the chair frame to prevent rotation of the insert restraining bar thereby coupling the insert to the plastic shell. This invention is an improvement of such patented construction.
It has been desirable to provide a fastening means for inserts for plastic shells which provides for correct replacement of the inserts while reducing labor cost and time out-of-service for the bus. The fastening means for inserts desirably restrains the insert when the insert is subjected to an operational environment including twisting and vibrational forces. Furthermore, it has been desirable to be able to use such a fastening means whenever replacement of inserts is desired because of wear, vandalism, a desire to change color schemes or some other reason.